When you leave reddit, a corporatised and astroturfed bot farm you're gonna get less liberal and right wing stuff that only existed to make money or exert political influence.
If you're really upset by it you can filter lemmy.ml which is gonna be the main source of left wing posting.
I'd rather OP just goes back to reddit though honestly. There are already a surprising amount of capitalist bootlickers on Lemmy for an open source platform
Tbf reddit used to be a lot more lefty. Back when Shit Reddit Says was the dominant subculture it was a lot of fun... But then Steve Bannon wanted Trump to be president and SRS lost the war against red hats and bots.